// SPDX-License-Identifier: GPL-2.0-or-later /* * 60xx Single Board Computer Watchdog Timer driver for Linux 2.2.x * * Based on acquirewdt.c by Alan Cox. * * The author does NOT admit liability nor provide warranty for * any of this software. This material is provided "AS-IS" in * the hope that it may be useful for others. * * (c) Copyright 2000 Jakob Oestergaard <jakob@unthought.net> * * 12/4 - 2000 [Initial revision] * 25/4 - 2000 Added /dev/watchdog support * 09/5 - 2001 [smj@oro.net] fixed fop_write to "return 1" * on success * 12/4 - 2002 [rob@osinvestor.com] eliminate fop_read * fix possible wdt_is_open race * add CONFIG_WATCHDOG_NOWAYOUT support * remove lock_kernel/unlock_kernel pairs * added KERN_* to printk's * got rid of extraneous comments * changed watchdog_info to correctly reflect what * the driver offers * added WDIOC_GETSTATUS, WDIOC_GETBOOTSTATUS, * WDIOC_SETTIMEOUT, WDIOC_GETTIMEOUT, and * WDIOC_SETOPTIONS ioctls * 09/8 - 2003 [wim@iguana.be] cleanup of trailing spaces * use module_param * made timeout (the emulated heartbeat) a * module_param * made the keepalive ping an internal subroutine * made wdt_stop and wdt_start module params * added extra printk's for startup problems * added MODULE_AUTHOR and MODULE_DESCRIPTION info * * This WDT driver is different from the other Linux WDT * drivers in the following ways: * *) The driver will ping the watchdog by itself, because this * particular WDT has a very short timeout (one second) and it * would be insane to count on any userspace daemon always * getting scheduled within that time frame. */ #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt #include <linux/module.h> #include <linux/moduleparam.h> #include <linux/types.h> #include <linux/timer.h> #include <linux/jiffies.h> #include <linux/miscdevice.h> #include <linux/watchdog.h> #include <linux/fs.h> #include <linux/ioport.h> #include <linux/notifier.h> #include <linux/reboot.h> #include <linux/init.h> #include <linux/io.h> #include <linux/uaccess.h> #define OUR_NAME "sbc60xxwdt" #define PFX OUR_NAME ": " /* * You must set these - The driver cannot probe for the settings */ static int wdt_stop = 0x45; module_param(wdt_stop, int, 0); MODULE_PARM_DESC(wdt_stop, "SBC60xx WDT 'stop' io port (default 0x45)"); static int wdt_start = 0x443; module_param(wdt_start, int, 0); MODULE_PARM_DESC(wdt_start, "SBC60xx WDT 'start' io port (default 0x443)"); /* * The 60xx board can use watchdog timeout values from one second * to several minutes. The default is one second, so if we reset * the watchdog every ~250ms we should be safe. */ #define WDT_INTERVAL (HZ/4+1) /* * We must not require too good response from the userspace daemon. * Here we require the userspace daemon to send us a heartbeat * char to /dev/watchdog every 30 seconds. * If the daemon pulses us every 25 seconds, we can still afford * a 5 second scheduling delay on the (high priority) daemon. That * should be sufficient for a box under any load. */ #define WATCHDOG_TIMEOUT 30 /* 30 sec default timeout */ static int timeout = WATCHDOG_TIMEOUT; /* in seconds, multiplied by HZ to get seconds to wait for a ping */ module_param(timeout, int, 0); MODULE_PARM_DESC(timeout, "Watchdog timeout in seconds. (1<=timeout<=3600, default=" __MODULE_STRING(WATCHDOG_TIMEOUT) ")"); static bool nowayout = WATCHDOG_NOWAYOUT; module_param(nowayout, bool, 0); MODULE_PARM_DESC(nowayout, "Watchdog cannot be stopped once started (default=" __MODULE_STRING(WATCHDOG_NOWAYOUT) ")"); static void wdt_timer_ping(struct timer_list *); static DEFINE_TIMER(timer, wdt_timer_ping); static unsigned long next_heartbeat; static unsigned long wdt_is_open; static char wdt_expect_close; /* * Whack the dog */ static void wdt_timer_ping(struct timer_list *unused) { /* If we got a heartbeat pulse within the WDT_US_INTERVAL * we agree to ping the WDT */ if (time_before(jiffies, next_heartbeat)) { /* Ping the WDT by reading from wdt_start */ inb_p(wdt_start); /* Re-set the timer interval */ mod_timer(&timer, jiffies + WDT_INTERVAL); } else pr_warn("Heartbeat lost! Will not ping the watchdog\n"); } /* * Utility routines */ static void wdt_startup(void) { next_heartbeat = jiffies + (timeout * HZ); /* Start the timer */ mod_timer(&timer, jiffies + WDT_INTERVAL); pr_info("Watchdog timer is now enabled\n"); } static void wdt_turnoff(void) { /* Stop the timer */ del_timer_sync(&timer); inb_p(wdt_stop); pr_info("Watchdog timer is now disabled...\n"); } static void wdt_keepalive(void) { /* user land ping */ next_heartbeat = jiffies + (timeout * HZ); } /* * /dev/watchdog handling */ static ssize_t fop_write(struct file *file, const char __user *buf, size_t count, loff_t *ppos) { /* See if we got the magic character 'V' and reload the timer */ if (count) { if (!nowayout) { size_t ofs; /* note: just in case someone wrote the magic character five months ago... */ wdt_expect_close = 0; /* scan to see whether or not we got the magic character */ for (ofs = 0; ofs != count; ofs++) { char c; if (get_user(c, buf + ofs)) return -EFAULT; if (c == 'V') wdt_expect_close = 42; } } /* Well, anyhow someone wrote to us, we should return that favour */ wdt_keepalive(); } return count; } static int fop_open(struct inode *inode, struct file *file) { /* Just in case we're already talking to someone... */ if (test_and_set_bit(0, &wdt_is_open)) return -EBUSY; if (nowayout) __module_get(THIS_MODULE); /* Good, fire up the show */ wdt_startup(); return stream_open(inode, file); } static int fop_close(struct inode *inode, struct file *file) { if (wdt_expect_close == 42) wdt_turnoff(); else { del_timer(&timer); pr_crit("device file closed unexpectedly. Will not stop the WDT!\n"); } clear_bit(0, &wdt_is_open); wdt_expect_close = 0; return 0; } static long fop_ioctl(struct file *file, unsigned int cmd, unsigned long arg) { void __user *argp = (void __user *)arg; int __user *p = argp; static const struct watchdog_info ident = { .options = WDIOF_KEEPALIVEPING | WDIOF_SETTIMEOUT | WDIOF_MAGICCLOSE, .firmware_version = 1, .identity = "SBC60xx", }; switch (cmd) { case WDIOC_GETSUPPORT: return copy_to_user(argp, &ident, sizeof(ident)) ? -EFAULT : 0; case WDIOC_GETSTATUS: case WDIOC_GETBOOTSTATUS: return put_user(0, p); case WDIOC_SETOPTIONS: { int new_options, retval = -EINVAL; if (get_user(new_options, p)) return -EFAULT; if (new_options & WDIOS_DISABLECARD) { wdt_turnoff(); retval = 0; } if (new_options & WDIOS_ENABLECARD) { wdt_startup(); retval = 0; } return retval; } case WDIOC_KEEPALIVE: wdt_keepalive(); return 0; case WDIOC_SETTIMEOUT: { int new_timeout; if (get_user(new_timeout, p)) return -EFAULT; /* arbitrary upper limit */ if (new_timeout < 1 || new_timeout > 3600) return -EINVAL; timeout = new_timeout; wdt_keepalive(); } fallthrough; case WDIOC_GETTIMEOUT: return put_user(timeout, p); default: return -ENOTTY; } } static const struct file_operations wdt_fops = { .owner = THIS_MODULE, .llseek = no_llseek, .write = fop_write, .open = fop_open, .release = fop_close, .unlocked_ioctl = fop_ioctl, .compat_ioctl = compat_ptr_ioctl, }; static struct miscdevice wdt_miscdev = { .minor = WATCHDOG_MINOR, .name = "watchdog", .fops = &wdt_fops, }; /* * Notifier for system down */ static int wdt_notify_sys(struct notifier_block *this, unsigned long code, void *unused) { if (code == SYS_DOWN || code == SYS_HALT) wdt_turnoff(); return NOTIFY_DONE; } /* * The WDT needs to learn about soft shutdowns in order to * turn the timebomb registers off. */ static struct notifier_block wdt_notifier = { .notifier_call = wdt_notify_sys, }; static void __exit sbc60xxwdt_unload(void) { wdt_turnoff(); /* Deregister */ misc_deregister(&wdt_miscdev); unregister_reboot_notifier(&wdt_notifier); if ((wdt_stop != 0x45) && (wdt_stop != wdt_start)) release_region(wdt_stop, 1); release_region(wdt_start, 1); } static int __init sbc60xxwdt_init(void) { int rc = -EBUSY; if (timeout < 1 || timeout > 3600) { /* arbitrary upper limit */ timeout = WATCHDOG_TIMEOUT; pr_info("timeout value must be 1 <= x <= 3600, using %d\n", timeout); } if (!request_region(wdt_start, 1, "SBC 60XX WDT")) { pr_err("I/O address 0x%04x already in use\n", wdt_start); rc = -EIO; goto err_out; } /* We cannot reserve 0x45 - the kernel already has! */ if (wdt_stop != 0x45 && wdt_stop != wdt_start) { if (!request_region(wdt_stop, 1, "SBC 60XX WDT")) { pr_err("I/O address 0x%04x already in use\n", wdt_stop); rc = -EIO; goto err_out_region1; } } rc = register_reboot_notifier(&wdt_notifier); if (rc) { pr_err("cannot register reboot notifier (err=%d)\n", rc); goto err_out_region2; } rc = misc_register(&wdt_miscdev); if (rc) { pr_err("cannot register miscdev on minor=%d (err=%d)\n", wdt_miscdev.minor, rc); goto err_out_reboot; } pr_info("WDT driver for 60XX single board computer initialised. timeout=%d sec (nowayout=%d)\n", timeout, nowayout); return 0; err_out_reboot: unregister_reboot_notifier(&wdt_notifier); err_out_region2: if (wdt_stop != 0x45 && wdt_stop != wdt_start) release_region(wdt_stop, 1); err_out_region1: release_region(wdt_start, 1); err_out: return rc; } module_init(sbc60xxwdt_init); module_exit(sbc60xxwdt_unload); MODULE_AUTHOR("Jakob Oestergaard <jakob@unthought.net>"); MODULE_DESCRIPTION("60xx Single Board Computer Watchdog Timer driver"); MODULE_LICENSE("GPL");